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          <th colspan="3" align="center">Chapter 5. 
                The DbEnv Handle
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            <h2 class="title"><a id="env"></a>Chapter 5. 
                The DbEnv Handle
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      <p>
        The <code class="classname">DbEnv</code> object is the handle for a Berkeley DB environment
        — a collection including support for some or all of caching, locking, logging and
        transaction subsystems, as well as databases and log files. Methods of the
        <code class="classname">DbEnv</code> handle are used to configure the environment as well as
        to operate on subsystems and databases in the environment.
    </p>
      <p>
        <code class="classname">DbEnv</code> handles 
        
        are opened using the <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>
        method.
    </p>
      <p>
        When you are done using your environment, close it using the 
        <a class="xref" href="envclose.html" title="DbEnv::close()">DbEnv::close()</a> method. Before closing your
        environment, make sure all open database handles are closed first. See the
        <a class="xref" href="dbclose.html" title="Db::close()">Db::close()</a> method for more information.
    </p>
      <div class="sect1" lang="en" xml:lang="en">
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              <h2 class="title" style="clear: both"><a id="envlist"></a>Database Environments and Related Methods</h2>
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                <th>Database Environment Operations</th>
                <th>Description</th>
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            </thead>
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              <tr>
                <td>
                  <a class="xref" href="envbackup.html" title="DbEnv::backup()">DbEnv::backup()</a>
                </td>
                <td>Hot back up an entire environment</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envclose.html" title="DbEnv::close()">DbEnv::close()</a>
                </td>
                <td>Close an environment</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envcreate.html" title="DbEnv">DbEnv</a>
                </td>
                <td>Create an environment handle</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envdbbackup.html" title="DbEnv::dbbackup()">DbEnv::dbbackup()</a>
                </td>
                <td>Hot back up a single environment file</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envdbremove.html" title="DbEnv::dbremove()">DbEnv::dbremove()</a>
                </td>
                <td>Remove a database</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envdbrename.html" title="DbEnv::dbrename()">DbEnv::dbrename()</a>
                </td>
                <td>Rename a database</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="enverr.html" title="DbEnv::err()">DbEnv::err()</a>
                </td>
                <td>Error message</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envfailchk.html" title="DbEnv::failchk()">DbEnv::failchk()</a>
                </td>
                <td>Check for thread failure</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envfileid_reset.html" title="DbEnv::fileid_reset()">DbEnv::fileid_reset()</a>
                </td>
                <td>Reset database file IDs</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envfullversion.html" title="DbEnv::full_version()">DbEnv::full_version()</a>
                </td>
                <td>Return full version information</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="dbgetenv.html" title="Db::get_env()">Db::get_env()</a>
                </td>
                <td>Return the Db's underlying DbEnv handle </td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envget_home.html" title="DbEnv::get_home()">DbEnv::get_home()</a>
                </td>
                <td>Return environment's home directory</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envget_open_flags.html" title="DbEnv::get_open_flags()">DbEnv::get_open_flags()</a>
                </td>
                <td>Return flags with which the environment was opened</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envlog_verify.html" title="DbEnv::log_verify()">DbEnv::log_verify()</a>
                </td>
                <td>Verify log files of an environment.</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envlsn_reset.html" title="DbEnv::lsn_reset()">DbEnv::lsn_reset()</a>
                </td>
                <td>Reset database file LSNs</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>
                </td>
                <td>Open an environment</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envremove.html" title="DbEnv::remove()">DbEnv::remove()</a>
                </td>
                <td>Remove an environment</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envstat.html" title="DbEnv::stat_print()">DbEnv::stat_print()</a>
                </td>
                <td>Environment statistics</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envstrerror.html" title="DbEnv::strerror()">DbEnv::strerror()</a>
                </td>
                <td>Error strings</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envversion.html" title="DbEnv::version()">DbEnv::version()</a>
                </td>
                <td>Return version information</td>
              </tr>
              <tr>
                <td colspan="2">
                  <span class="bold">
                    <strong>Environment Configuration</strong>
                  </span>
                </td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envadd_data_dir.html" title="DbEnv::add_data_dir()">DbEnv::add_data_dir()</a>
                </td>
                <td>Add an environment data directory</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_alloc.html" title="DbEnv::set_alloc()">DbEnv::set_alloc()</a>
                </td>
                <td>Set local space allocation functions</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_app_dispatch.html" title="DbEnv::set_app_dispatch()">DbEnv::set_app_dispatch()</a>
                </td>
                <td>Configure application recovery callback</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_backup_callbacks.html" title="DbEnv::set_backup_callbacks()">DbEnv::set_backup_callbacks()</a>, <a class="xref" href="envget_backup_callbacks.html" title="DbEnv::get_backup_callbacks()">DbEnv::get_backup_callbacks()</a></td>
                <td>Set/get callbacks used for environment hot backups</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_backup_config.html" title="DbEnv::set_backup_config()">DbEnv::set_backup_config()</a>, <a class="xref" href="envget_backup_config.html" title="DbEnv::get_backup_config()">DbEnv::get_backup_config()</a></td>
                <td>Set/get environment hot backup configuration options</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_data_dir.html" title="DbEnv::set_data_dir()">DbEnv::set_data_dir()</a>, <a class="xref" href="envget_data_dirs.html" title="DbEnv::get_data_dirs()">DbEnv::get_data_dirs()</a></td>
                <td>Set/get the environment data directory</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_create_dir.html" title="DbEnv::set_create_dir()">DbEnv::set_create_dir()</a>, <a class="xref" href="envget_create_dir.html" title="DbEnv::get_create_dir()">DbEnv::get_create_dir()</a></td>
                <td>Add an environment data directory</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_encrypt.html" title="DbEnv::set_encrypt()">DbEnv::set_encrypt()</a>, <a class="xref" href="envget_encrypt_flags.html" title="DbEnv::get_encrypt_flags()">DbEnv::get_encrypt_flags()</a></td>
                <td>Set/get the environment cryptographic key</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envevent_notify.html" title="DbEnv::set_event_notify()">DbEnv::set_event_notify()</a>
                </td>
                <td>Set event notification callback</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_errcall.html" title="DbEnv::set_errcall()">DbEnv::set_errcall()</a>
                </td>
                <td>Set error message callbacks</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_errfile.html" title="DbEnv::set_errfile()">DbEnv::set_errfile()</a>, <a class="xref" href="envget_errfile.html" title="DbEnv::get_errfile()">DbEnv::get_errfile()</a></td>
                <td>Set/get error message FILE</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_error_stream.html" title="DbEnv::set_error_stream()">DbEnv::set_error_stream()</a>
                </td>
                <td>Set C++ ostream used for error messages</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_errpfx.html" title="DbEnv::set_errpfx()">DbEnv::set_errpfx()</a>, <a class="xref" href="envget_errpfx.html" title="DbEnv::get_errpfx()">DbEnv::get_errpfx()</a></td>
                <td>Set/get error message prefix</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_feedback.html" title="DbEnv::set_feedback()">DbEnv::set_feedback()</a>
                </td>
                <td>Set feedback callback</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_flags.html" title="DbEnv::set_flags()">DbEnv::set_flags()</a>, <a class="xref" href="envget_flags.html" title="DbEnv::get_flags()">DbEnv::get_flags()</a></td>
                <td>Environment configuration</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_intermediate_dir_mode.html" title="DbEnv::set_intermediate_dir_mode()">DbEnv::set_intermediate_dir_mode()</a>, <a class="xref" href="envget_intermediate_dir_mode.html" title="DbEnv::get_intermediate_dir_mode()">DbEnv::get_intermediate_dir_mode()</a></td>
                <td>Set/get intermediate directory creation mode</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_isalive.html" title="DbEnv::set_isalive()">DbEnv::set_isalive()</a>
                </td>
                <td>Set thread is-alive callback</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_memory_init.html" title="DbEnv::set_memory_init()">DbEnv::set_memory_init()</a>, <a class="xref" href="envget_memory_init.html" title="DbEnv::get_memory_init()">DbEnv::get_memory_init()</a></td>
                <td>Set/get initial memory allocation</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_memory_max.html" title="DbEnv::set_memory_max()">DbEnv::set_memory_max()</a>, <a class="xref" href="envget_memory_max.html" title="DbEnv::get_memory_max()">DbEnv::get_memory_max()</a></td>
                <td>Set/get maximum memory allocation</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_metadata_dir.html" title="DbEnv::set_metadata_dir()">DbEnv::set_metadata_dir()</a>, <a class="xref" href="envget_metadata_dir.html" title="DbEnv::get_metadata_dir()">DbEnv::get_metadata_dir()</a></td>
                <td>Set/get the directory containing environment metadata </td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_message_stream.html" title="DbEnv::set_message_stream()">DbEnv::set_message_stream()</a>
                </td>
                <td>Set C++ ostream used for informational messages</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_msgcall.html" title="DbEnv::set_msgcall()">DbEnv::set_msgcall()</a>
                </td>
                <td>Set informational message callback</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_msgfile.html" title="DbEnv::set_msgfile()">DbEnv::set_msgfile()</a>, <a class="xref" href="envget_msgfile.html" title="DbEnv::get_msgfile()">DbEnv::get_msgfile()</a></td>
                <td>Set/get informational message FILE</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_shm_key.html" title="DbEnv::set_shm_key()">DbEnv::set_shm_key()</a>, <a class="xref" href="envget_shm_key.html" title="DbEnv::get_shm_key()">DbEnv::get_shm_key()</a></td>
                <td>Set/get system memory shared segment ID</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_thread_count.html" title="DbEnv::set_thread_count()">DbEnv::set_thread_count()</a>, <a class="xref" href="envget_thread_count.html" title="DbEnv::get_thread_count()">DbEnv::get_thread_count()</a></td>
                <td>Set/get approximate thread count</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_thread_id.html" title="DbEnv::set_thread_id()">DbEnv::set_thread_id()</a>
                </td>
                <td>Set thread of control ID function</td>
              </tr>
              <tr>
                <td>
                  <a class="xref" href="envset_thread_id_string.html" title="DbEnv::set_thread_id_string()">DbEnv::set_thread_id_string()</a>
                </td>
                <td>Set thread of control ID format function</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_timeout.html" title="DbEnv::set_timeout()">DbEnv::set_timeout()</a>, <a class="xref" href="envget_timeout.html" title="DbEnv::get_timeout()">DbEnv::get_timeout()</a></td>
                <td>Set/get lock and transaction timeout</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_tmp_dir.html" title="DbEnv::set_tmp_dir()">DbEnv::set_tmp_dir()</a>, <a class="xref" href="envget_tmp_dir.html" title="DbEnv::get_tmp_dir()">DbEnv::get_tmp_dir()</a></td>
                <td>Set/get the environment temporary file directory</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_verbose.html" title="DbEnv::set_verbose()">DbEnv::set_verbose()</a>, <a class="xref" href="envget_verbose.html" title="DbEnv::get_verbose()">DbEnv::get_verbose()</a></td>
                <td>Set/get verbose messages</td>
              </tr>
              <tr>
                <td><a class="xref" href="envset_cachesize.html" title="DbEnv::set_cachesize()">DbEnv::set_cachesize()</a>, <a class="xref" href="envget_cachesize.html" title="DbEnv::get_cachesize()">DbEnv::get_cachesize()</a></td>
                <td>Set/get the environment cache size</td>
              </tr>
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